US20140209027A1 - Showerhead having a detachable gas distribution plate - Google Patents

Abstract

Embodiments of showerheads having a detachable gas distribution plate are provided herein. In some embodiments, a showerhead for use in a semiconductor processing chamber may include a base having a first side and a second side; a gas distribution plate disposed proximate the second side of the base; a clamp disposed about a peripheral edge of the gas distribution plate to removably couple the gas distribution plate to the base; and a thermal gasket disposed between the base and gas distribution plate.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims benefit of U.S. provisional patent application Ser. No. 61/756,545, filed Jan. 25, 2013, which is herein incorporated by reference.
FIELD
• Embodiments of the present invention generally relate to semiconductor processing equipment.
BACKGROUND
• Conventional showerheads utilized in semiconductor process chambers (e.g., deposition chambers, etch chambers, or the like) typically include a gas distribution plate permanently bonded to a base. The gas distribution plate requires periodic replacement due to degradation caused by exposure to plasma during plasma processes. However, the inventors have observed that since the gas distribution plate is permanently bonded to the base, the entire showerhead assembly requires replacement in order to replace the gas distribution plate, thus making the replacement process costly.
• Therefore, the inventors have provided embodiments of an improved showerhead with detachable gas distribution plate.
SUMMARY
• Embodiments of showerheads having a detachable gas distribution plate are provided herein. In some embodiments, a showerhead for use in a semiconductor processing chamber may include a base having a first side and a second side; a gas distribution plate disposed proximate the second side of the base; a clamp disposed about a peripheral edge of the gas distribution plate to removably couple the gas distribution plate to the base; and a thermal gasket disposed between the base and gas distribution plate.
• In some embodiments, a process chamber may include a chamber body having a substrate support disposed within an inner volume of the chamber body; and a showerhead disposed within the inner volume of the chamber body opposite the substrate support. The showerhead includes: a base having a first side and an opposing second side, wherein the first side of the base is coupled to a component of the process chamber; a gas distribution plate disposed proximate the second side of the base; a clamp disposed about a peripheral edge of the gas distribution plate to removably couple the gas distribution plate to the base; and a thermal gasket disposed between the base and gas distribution plate.
• Other and further embodiments of the present invention are described below.
BRIEF DESCRIPTION OF THE DRAWINGS
• Embodiments of the present invention, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the invention depicted in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
• FIG. 1 depicts a showerhead with a gas distribution plate in accordance with some embodiments of the present invention.
• FIG. 2 depicts a process chamber suitable for use with a showerhead having a gas distribution plate in accordance with some embodiments of the present invention.
• To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
DETAILED DESCRIPTION
• Embodiments of showerheads having a detachable gas distribution plate are provided herein. In at least some embodiments, the inventive showerhead may advantageously allow for the removal and replacement of the gas distribution plate, thereby providing a showerhead having a longer useful life and a more cost efficient manner of replacing the gas distribution plate as compared to conventional showerheads having a permanently bonded gas distribution plate.
• FIG. 1 depicts a showerhead with a gas distribution plate in accordance with some embodiments of the present invention. Theshowerhead100 generally comprises abody102, agas distribution plate104 and aclamp110 configured to removably couple the gas distribution plate to thebody102.
• Thebody102 comprises afirst side150, asecond side140 and a plurality of throughholes116 formed in thebody102 extending from thefirst side150 to thesecond side140. The plurality of throughholes116 facilitate the passage of process gases through thebody102 to thegas distribution plate104. In some embodiments, the throughholes116 may be counter sunk (e.g., countersink118 shown) to reduce a residual electrical field at thethrough holes116 and to facilitate a more uniform gas flow to thegas distribution plate104. In some embodiments, acavity114 may be formed infirst side150 of thebody102 to facilitate more even distribution of process gases to the plurality of throughholes116. Thebody102 may be fabricated from any suitable process compatible material, for example, such as aluminum. By fabricating thebody102 from a conductive material such as aluminum, thebody102 may function as an electrode to facilitate, for example, the formation of a plasma from process gases provided to theshowerhead100.
• In some embodiments, one or more channels may be formed in the surfaces of thebody102 to accommodate one or more o-rings and/or RF gaskets (o-rings130,132,134 andRF gaskets108,126 shown). When present, the o-rings130,132,134 provide a seal between thebody102 andclamp110 or surfaces of the process chamber (not shown). The o-rings130,132,134, may be fabricated from any material suitable to facilitate the aforementioned seal, for example, rubber. TheRF gaskets108,126 facilitate conductivity of RF power from, for example, an RF source to thebody102 and theclamp110. For example, RF power may be provided from an RF power supply (such as the RF power supply248 described below) to a component coupled to thebody102 and in contact with one or more RF gaskets (e.g., RF gasket126). TheRF gaskets108,126 may be fabricated from any suitable conductive material, for example stainless steel.
• Thegas distribution plate104 facilitates distribution of process gases provided from thebody102 to, for example, a processing volume of a process chamber via a plurality ofgas distribution holes142 formed in thegas distribution plate104. Thegas distribution holes142 may be arranged in any manner suitable to provide a desired distribution of process gases. For example, in some embodiments, thegas distribution holes142 may be arranged in clusters disposed about the throughholes116 of thebody102 when thegas distribution plate104 is coupled to thebody102.
• Thegas distribution plate104 may be fabricated from any material suitable to resist degradation during exposure to a plasma (e.g., a plasma formed in a process chamber during processing). For example in some embodiments, thegas distribution plate104 may be fabricated from single crystalline silicon (Si). Single crystal silicon is not typically used as a material for the gas distribution plate at least in part due to it having a faster etch rate as compared to silicon carbide, a favored material. However, the inventors have observed that single crystalline silicon is less susceptible to surface roughness change, arcing, and micro-masking, and further provides better operability at elevated temperatures (e.g., higher than about150 degrees Celsius) as compared to conventional materials utilized to fabricate gas distribution plates, for example, such as silicon carbide (SiC). In addition, single crystal silicon is more readily available and obtainable at a lower cost as compared to the conventional materials. In addition, in embodiments where theshowerhead100 is used in substrate processes involving silicon-containing gases, fabricating thegas distribution plate104 from silicon reduces the instances of contamination due to degradation of thegas distribution plate104.
• Thegas distribution plate104 may have any suitable thickness sufficient to provide a desired gas distribution and suitable useful functional life. In addition, in some embodiments, thegas distribution plate104 may have a suitable thickness sufficient to ensure continuous contact with one or more thermal gaskets (threethermal gaskets120,122,124 shown) disposed between thegas distribution plate104 and thebody102 when thegas distribution plate104 is coupled to thebody102. For example, in some embodiments, the thickness of thegas distribution plate104 may be selected such that an amount of bowing of thegas distribution plate104 caused by the forces provided by theclamp110 at the edge of thegas distribution plate104 is less than an amount of deformation of thethermal gaskets120,122,124 when compressed, thereby ensuring continuous contact with each of thethermal gaskets120,122,124 when clamped. Alternatively, or in combination, in some embodiments, the thickness of thegas distribution plate104 may be selected to provide an aspect ratio of thegas distribution holes142 suitable to reduce plasma penetration and improve the useful functional life of thegas distribution plate104. For example, in embodiments where thegas distribution holes142 have a diameter of about 0.5 mm, thegas distribution plate104 may have a thickness of about 9 mm.
• Theclamp110 facilitates coupling thegas distribution plate104 to thebody102. In some embodiments, theclamp110 facilities such coupling via afastener106 provided to athrough hole136 formed in thebody102 corresponding to a threadedhole138 formed in the clamp. Theclamp110 may be fabricated from any process compatible conductive material, for example aluminum. In some embodiments, theclamp110 may coated with a spray coating (e.g., yttria (Y₂O₃)) to reduce degradation of theclamp110 in a plasma environment.
• In some embodiments, theclamp110 may include one or more channels formed in surfaces of theclamp110 to accommodate one or more o-rings and RF gaskets (o-ring128 andRF gasket148 shown). When present, the o-ring128 provides cushioning to thegas distribution plate104 to prevent breakage of thegas distribution plate104 when clamped to thebody102. When present, theRF gasket148 facilitates conductivity of RF power from thebody102, through theclamp110, and to thegas distribution plate104, thereby allowing thegas distribution plate104 to function as an RF electrode. Providing the RF current path to thegas distribution plate104 also shields agap146 between thebody102 and thegas distribution plate104, which reduces arcing, for example, at thethrough holes116 of thebody102. The o-ring128 andRF gasket148 may be fabricated from any suitable material, for example such as the materials discussed above with respect to the o-rings130,132,134, andRF gaskets108,126.
• In some embodiments, thethermal gaskets120,122,124 may be disposed between thebody102 andgas distribution plate104. When present, thethermal gaskets120,122,124 may facilitate a heat exchange between thebody102 and thegas distribution plate104, for example, to provide a more uniform thermal gradient across thegas distribution plate104. In addition, thethermal gaskets120,122,124 may provide thegap146 between thebody102 and thegas distribution plate104 and define separate plenums (e.g., zones) for groups of throughholes116 and corresponding gas distribution holes142.
• Thethermal gaskets120,122,124 may be fabricated from any compressible, thermally conductive material having low out-gassing at process pressures and temperatures (e.g., vacuum conditions and temperatures at or above about 150 degrees Celsius). For example, in some embodiments, the gasket may comprise a silicon containing material. Thethermal gaskets120,122,124 may have any shape suitable to maintain contact between thebody102 and thegas distribution plate104. For example, in some embodiments, thethermal gaskets120,122,124 may be a plurality of concentric rings having a rectangular cross section as shown inFIG. 1. In some embodiments, the geometry of thethermal gaskets120,122,124 may be optimized to accommodate for a difference in distance between thebody102 and thegas distribution plate104 when clamped together due to the forces provided by theclamp110 at the edge of the gas distribution plate104 (e.g., bowing of the gas distribution plate104).
• In some embodiments, aprotective ring112 may be disposed about the showerhead to shield portions of thebody102,clamp110 andgas distribution plate104. Theprotective ring112 may be fabricated from any suitable process compatible material, for example, quartz (SiO₂).
• FIG. 2 depicts a schematic view of anillustrative process chamber200 suitable for use with a showerhead in accordance with some embodiments of the present invention. Exemplary process chambers may include the ENABLER®, ENABLER®E5, ADVANTEDGE™, or other process chambers, available from Applied Materials, Inc. of Santa Clara, Calif. Other suitable process chambers having, or being modified to have, showerheads may similarly benefit from the present invention.
• In some embodiments, theprocess chamber200 may generally comprise achamber body202 having asubstrate support pedestal208 for supporting asubstrate210 thereupon disposed within aninner volume205 of the chamber body, and anexhaust system220 for removing excess process gases, processing by-products, or the like, from theinner volume205 of thechamber body202.
• In some embodiments, anupper liner264 and alower liner266 may cover the interior of thechamber body202 to protect thechamber body202 during processing. In some embodiments, thechamber body202 has aninner volume205 that may include aprocessing volume204. Theprocessing volume204 may be defined, for example, between thesubstrate support pedestal208 and a showerhead214 (e.g.,showerhead100 described above) and/or nozzles provided at desired locations. In some embodiments, agas supply288 may provide one or more process gases to theshowerhead214 for distribution of the one or more process gases to theprocessing volume204 of thechamber body202.
• In some embodiments, thesubstrate support pedestal208 may include a mechanism that retains or supports thesubstrate210 on the surface of thesubstrate support pedestal208, such as an electrostatic chuck, a vacuum chuck, a substrate retaining clamp, or the like. Alternatively, or in combination, in some embodiments, thesubstrate support pedestal208 may include mechanisms for controlling the substrate temperature (such as heating and/or cooling devices, not shown) and/or for controlling the species flux and/or ion energy proximate the substrate surface. For example, in some embodiments, thesubstrate support pedestal208 may include an electrode240 and one or more power sources (twobias power sources238,244) coupled to the electrode240 viarespective matching networks236,262. For example, thesubstrate support pedestal208 may be configured as a cathode coupled to abias power source244 via amatching network262. The above described bias power sources (e.g., biaspower sources238,244) may be capable of producing up to 12,000 W at a frequency of about 2 MHz, or about 13.56 MHz, or about 60 Mhz. The at least one bias power source may provide either continuous or pulsed power. In some embodiments, the bias power source alternatively may be a DC or pulsed DC source.
• In some embodiments, thesubstrate support pedestal208 may include asubstrate support ring280 disposed atop thesubstrate support pedestal208 and configured to support at least a portion of thesubstrate210 during processing. In some embodiments, one or more rings (insertring278 andbarrier ring242 shown) may be disposed about thesubstrate support pedestal208. The one or more rings may be fabricated from any suitable process compatible material. For example, in some embodiments, the insert ring may be fabricated from silicon (Si). In some embodiments, thebarrier ring242 may be fabricated from quartz (SiO₂). In some embodiments, a groundedmesh260 may be disposed about the periphery of thesubstrate support pedestal208 and coupled to thechamber body202.
• Thesubstrate210 may enter thechamber body202 via anopening212 in a wall of thechamber body202. Theopening212 may be selectively sealed via aslit valve218, or other mechanism for selectively providing access to the interior of the chamber through theopening212. Thesubstrate support pedestal208 may be coupled to alift mechanism234 that may control the position of thesubstrate support pedestal208 between a lower position (as shown) suitable for transferring substrates into and out of the chamber via theopening212 and a selectable upper position suitable for processing. The process position may be selected to maximize process uniformity for a particular process. When in at least one of the elevated processing positions, thesubstrate support pedestal208 may be disposed above theopening212 to provide a symmetrical processing region.
• In some embodiments, a protective ring206 (e.g., theprotective ring112 described above) may be disposed about, and covering at least a portion of, theshowerhead214, for example, such as the body294 (e.g.,body102 described above) or the gas distribution plate296 (e.g., thegas distribution plate104 described above) of theshowerhead214. In some embodiments, theprotective ring206 may be supported by theupper liner264.
• In some embodiments, theshowerhead214 may be coupled to and/or supported by, a chiller plate284. When present, the chiller plate284 facilitates control over a temperature of theshowerhead214 during processing. In some embodiments, the chiller plate284 comprises a plurality of channels (not shown) formed in the chiller plate284 to allow a temperature control fluid provided by a temperature control fluid supply (chiller)290 to flow through the chiller plate284 to facilitate the control over the temperature of theshowerhead214.
• In some embodiments, one or more coils (inner coil274 andouter coil272 shown) may be disposed above and/or proximate a peripheral edge of theshowerhead214. When present, the one or more coils may facilitate shaping a plasma formed within theprocessing volume204 of theprocess chamber200.
• In some embodiments, anRF power source286 provides RF power to thechiller plate270 and/or theshowerhead214 via acoaxial stub292. Thecoaxial stub292 is a fixed impedance matching network having a characteristic impedance, resonance frequency, and provides an approximate impedance match between theshowerhead214 and theRF power source286. In some embodiments, thecoaxial stub292 generally comprises an innercylindrical conductor298, an outercylindrical conductor201 and aninsulator203 filling the space between the innercylindrical conductor298 and the outercylindrical conductor201.
• The innercylindrical conductor298 and the outercylindrical conductor201 may be constructive of any suitable conductive material capable of withstanding the particular process environment. For example, in some embodiments, the innercylindrical conductor298 and the outercylindrical conductor201 may be fabricated from nickel-coated aluminum. One ormore taps221 are provided at particular points along the axial length of thecoaxial stub292 for applying RF power from theRF power source286 to thecoaxial stub292. AnRF power terminal207 and theRF return terminal209 of theRF power source286 are connected at thetap221 on thecoaxial stub292 to the innercylindrical conductor298 and the outercylindrical conductor201, respectively. A terminatingconductor211 at thefar end213 of thecoaxial stub292 shorts the innercylindrical conductor298 and the outercylindrical conductor201 together, so that thecoaxial stub292 is shorted at itsfar end213. At thenear end215 of thecoaxial stub292, the outercylindrical conductor201 is connected to thechamber body202 via an annular conductive housing orsupport276, while the innercylindrical conductor298 is connected to thechiller plate270 and/orshowerhead214 via aconductive cylinder217. In some embodiments, adielectric ring219, is disposed between and separates theconductive cylinder217 and thechiller plate270.
• Theexhaust system220 generally includes apumping plenum224 and one or more conduits that couple thepumping plenum224 to the inner volume205 (and generally, the processing volume204) of thechamber body202, for example via one ormore inlets222. Avacuum pump228 may be coupled to thepumping plenum224 via a pumpingport226 for pumping out the exhaust gases from thechamber body202. Thevacuum pump228 may be fluidly coupled to anexhaust outlet232 for routing the exhaust as required to appropriate exhaust handling equipment. A valve230 (such as a gate valve, or the like) may be disposed in thepumping plenum224 to facilitate control of the flow rate of the exhaust gases in combination with the operation of thevacuum pump228. Although a z-motion gate valve is shown, any suitable, process compatible valve for controlling the flow of the exhaust may be utilized.
• To facilitate control of theprocess chamber200 as described above, thecontroller250 may be one of any form of general-purpose computer processor that can be used in an industrial setting for controlling various chambers and sub-processors. The memory, or computer-readable medium,256 of theCPU252 may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. Thesupport circuits254 are coupled to theCPU252 for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry and subsystems, and the like.
• One or more methods and/or processes may generally be stored in thememory256 as asoftware routine258 that, when executed by theCPU252, causes theprocess chamber200 to perform the processes methods and/or processes. Thesoftware routine258 may also be stored and/or executed by a second CPU (not shown) that is remotely located from the hardware being controlled by theCPU252. Some or all of the method of the present invention may also be performed in hardware. As such, the methods and/or processes may be implemented in software and executed using a computer system, in hardware as, e.g., an application specific integrated circuit or other type of hardware implementation, or as a combination of software and hardware. Thesoftware routine258 may be executed after thesubstrate210 is positioned on thesubstrate support pedestal208. Thesoftware routine258, when executed by theCPU252, transforms the general purpose computer into a specific purpose computer (controller)250 that controls the chamber operation such that the methods disclosed herein are performed.
• Thus, embodiments of a showerhead having a detachable gas distribution plate have been provided herein. Embodiments of the inventive showerhead may advantageously provide a longer useful life and a more cost efficient manner of replacing the gas distribution plate as compared to conventional showerheads.
• While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.

Claims (20)

1. A showerhead for use in a semiconductor processing chamber, comprising:

a base having a first side and an opposing second side;

a gas distribution plate disposed proximate the second side of the base;

a clamp disposed about a peripheral edge of the gas distribution plate to removably couple the gas distribution plate to the base; and

a thermal gasket disposed between the base and gas distribution plate.

2. The showerhead ofclaim 1, wherein the thermal gasket comprises a plurality of concentric rings disposed between the base and the gas distribution plate.

3. The showerhead ofclaim 1, wherein the gasket has a rectangular cross section.

4. The showerhead ofclaim 1, further comprising:

a ring disposed about the peripheral edge of the base and the clamp and extending over a portion of the clamp to cover at least a portion of the base and at least a portion of the gas distribution ring.

5. The showerhead ofclaim 1, further comprising a first RF gasket disposed between the clamp and the base.

6. The showerhead ofclaim 1, further comprising a second RF gasket disposed between the clamp and the gas distribution plate.

7. The showerhead ofclaim 1, wherein the base comprise a plurality of through holes extending from the first side to the second side of the base.

8. The showerhead ofclaim 7, wherein the base comprises a plenum formed in the first side of the base, the plenum fluidly coupled to the plurality of through holes.

9. The showerhead ofclaim 7, wherein an end of each of the plurality of through holes is countersunk into the base.

10. The showerhead ofclaim 1, wherein the gas distribution plate is fabricated from single crystalline silicon (Si).

11. A process chamber, comprising:

a chamber body having a substrate support disposed within an inner volume of the chamber body; and

a showerhead disposed within the inner volume of the chamber body opposite the substrate support, the showerhead comprising:

a base having a first side and an opposing second side, wherein the first side of the base is coupled to a component of the process chamber;

a gas distribution plate disposed proximate the second side of the base;

a clamp disposed about a peripheral edge of the gas distribution plate to removably couple the gas distribution plate to the base; and

a thermal gasket disposed between the base and gas distribution plate.

12. The process chamber ofclaim 11, wherein the component of the process chamber is a cooling plate, and wherein the cooling plate is coupled to a ceiling of the chamber body.

13. The process chamber ofclaim 11, wherein the thermal gasket comprises a plurality of concentric rings disposed between the base and the gas distribution plate.

14. The process chamber ofclaim 11, wherein the gasket has a rectangular cross section.

15. The process chamber ofclaim 11, further comprising:

a ring disposed about the peripheral edge of the base and the clamp and extending over a portion of the clamp to cover at least a portion of the base and at least a portion of the gas distribution ring.

16. The process chamber ofclaim 15, wherein the ring is supported by a liner disposed within the chamber body.

17. The process chamber ofclaim 11, further comprising a first RF gasket disposed between the clamp and the base.

18. The process chamber ofclaim 11, further comprising a second RF gasket disposed between the clamp and the gas distribution plate.

19. The process chamber ofclaim 11, wherein the base comprise a plurality of through holes extending from the first side to the second side of the base.

20. The process chamber ofclaim 11, wherein an end of each of the plurality of through holes is countersunk into the base.

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